Construction of distillation columns and like structures



April 22, 1958 M. G. F. JAMES ET AL 2,831,667

CONSTRUCTION OF DISTILLATION COLUMNS AND LIKE STRUCTURES Filed Aug. 2, 1955 2 Sheets-Sheet 1 V I) In en 07' M. afivgms i" P.

April 22, 1958 M. G. F. JAMES ET AL CONSTRUCTION OF DISTILLATION COLUMNS AND LIKE STRUCTURES 2 Sheets-Sheet 2 Filed Aug. 2, 1955 Atiorn llllllll CONSTRUCTION OF DISTILLATION COLUMNS AND LIKE STRUCTURES Maurice George Frederick James, Purley, and Ronald William Knott, West Green, Crawley, England, assignors to The A. P. V. Company Limited, London, England Application August 2, 1955, Serial No. 525,964 Claims priority, application Great Britain August 6, 1954 2 Claims. (Cl. 261-414) medium (or vapour, as it will be termed) which bubbles via the perforations through the downcoming medium (or liquid, as it will be termed) which is fed to the upper surface of the plates, the structures being arranged to provide seals to prevent the rising vapour from passing from one plate structure to the next above it, except by way of the perforations, and the structures also providing overflow weirs over which the downcoming liquid passes from one plate structure to that next below it.

The main object of this invention is to provide a perforated bubble plate structure of such a form as will provide improved operating conditions and which will facilitate construction, assembly and maintenance and will be little liable to derangement or improper setting.

According to one feature of the present invention an element for use in a bubble plate structure comprises a section having a perforated bubble strip, a feed duct below the strip to receive rising vapours, a transfer duct to receive liquid from the perforated strip, a weir device to regulate the depth of the liquid on the strip and a seal device to seal the flow space between the weir device and the transfer duct against rising vapour, the section being formed as a complete unit with assembly with other similar units.

It is preferred that the transfer duct shall be closed throughout its length, the ends alone being opened to enable downcoming liquid to be discharged from the section; this arrangement avoids splashing of the liquid as it is being transferred.

According to a further feature of the invention a perforated bubble plate structure comprises a framework which supports a number of sections as have been referred to, the sections being disposed in spaced relationship to provide between them fiow spaces for directing rising vapour to the feed ducts of the sections at each side of the feed spaces. The sections, in making up such a structure, can be detachably secured to the framework.

As the sections in accordance with this invention are self-contained units including the seal, they can be accurately defined and produced under workshop conditions, so resulting in a section which will afiord uniform operat ing conditions.

The invention is illustrated in one construction in the accompanying drawings: in those drawings, Figure l is apart plan view of one perforated bubble plate strutcure which forms one level in a column having a number of such structures, Figure 2 is a section taken on the line IIII, Figure 1; Figure 3 is a section taken on the line llllll,

Figure 1; and Figure 4 is a transverse section of one of those sections and the adjacent parts.

Referring to the drawings, a distillation column comprises a number of superposed perforated bubble plate structures indicated generally by the reference 1, the structures being housed in a cylindrical outer casing 2 having supporting posts 3 which carry main ring frames 4 one for each structure 1, the rings 4 being sealed at their peripheries to the inner wall of the casing 2 as for example by packing 5, and the rings having transverse stretchers 6. 4

Each structure 1 comprises a number of sections denoted generally by the reference 7, the various sections being laid parallel with one another and supported by both the ring frames 4 and the transverse stretchers 6.

Each section 7 consists of a'liquid transfer duct 8 which is formed by a length '8' of metal of U shape, and a vapour feed duct 9 which is formed by a length 10 of metal plate having its longitudinal edges rolled up at 11 to form the duct, the base wall of the feed duct 9 closing the transfer duct 8 formed by the plate 8.

In the feed duct is supported a perforated met-a1 strip 12 I which forms the bubble plate of the section. This perforated plate is supported above the base of the feed duct 9, and centrally of its length the feed duct 9 is formed with an opening into which is inserted a stepped combined weir and trap component 13. This component can for example be cylindrical as is shown in the drawings and has a larger diameter 14 which extends above the perforated plate 12 to provide an overflow weir for the downcoming liquid and .a smaller diameter part 15 which extends through an opening in the base of the transfer duct 8, which has a sump or well'16 into which I the lower end of this smaller diameter part 15 extends; this smaller diameter part 15 and the well 16 provide the seal or trap against the flow of rising vapour at the point of discharge of the downcoming liquid.

This component 13 thus provides a central transfer point at which downcoming liquid flowing from the perforated strip 12 at each side of the component can pass over the weir l4 and through the seal l5, l6 and thence each way along the section through the closed transfer ducts 8, whence it discharges to the structure next below it through the open ends of the duct 8: the open ends of the transfer ducts of one structure are in alignment with a ring trough 20 in the structure below so that the downcoming liquid passes from the open ends to the trough which forms a weir over which the liquid is distributed to the perforated plates 12.

The component parts 8', it) and 12 of the self-com tained section are connected together in the required spaced relationship by bolts 17 with spacing tubes or nutson them so that the various component parts of the section can be detached.

The various sections required to ma e up a complete plate structure are preferably as shown secured in parallel relationship to the supporting framework. The sections can be secured by bolts which enable the sections individually to be removed; the sections are in spaced relationship as is shown in the drawings so as to provide between them flow openings F for the rising vapour. 'Disposed over the rolled up longitudinal edges 11 of the feed ducts 9 are hoods 18 which span the gap between the rolled up edges of adjacent sections, the hoods being separately secured in position detach-ably by bolts 19 which pull the edges of the hoods down on to the edges of the perforated plates 12; these hoods compel the rising vapour to pass through the passages F to the passage defined between the hoods l3 and the two rolled up edges 11 of the feed ducts 9 so that the rising vapour is compelled in passing from a structure at one level to pass through the feed ducts 9 and thence through the Patented Apr. 22, 1958 perforations in the strips 12 to reach the structure next above it.

It will be understood that the liquid which passes down the column 2 is received by the ring trough 20 of each structure and passes over the weir provided by the trough and thence is distributed to the surfaces of the various perforated strips 12 and flows over those surfaces at a minimum depth controlled by the weirs 14: the vapours rising in the column pass via the hoods 13 to the vapour ducts 9 and thence bubble up through the perforations in the strips 12 through the layer of liquid on the strips. The rising vapours are prevented from passing, at the point at which the downcoming liquid is discharging from one perforated strip to another, by the liquid seal which is formed at the member 15.

It will be apparent that with the construction shown, the various sections making up the various structures 1 are completely self-contained and their parts can be set under factory conditions, this being of importance especially with regard to the seal formed by the parts 15, 16, which can thus be arranged to have a constant seal to ensure uniformity of flow over the total area of each structure.

In addition, because the U-shaped liquid transfer duct 8 of each section is closed by the base of the plate It? constituting the vapour duct 9, there is no possibility that the downcoming liquid can splash out of the trough and so recirculate.

Moreover, the sections are accessible so as to be individually removable.

We claim:

1. For use in a distillation column of the bubble plate type, a contact tray comprising a plurality of units each of which comprises a length of perforated strip forming the bubble plate, a first longitudinal trough wider than the strip, means supporting the strip in the trough and spaced from its base to leave a vapor duct between them, the edges of the trough extending at each side beyond the strip to form one part of a vapor deflector, a second trough open at both ends to discharge liquid therefrom, means securing the second trough below the first trough to be closed on the topside from end to end by said first trough to form a liquid transfer duct, an overflow weir disposed between the ends of the perforated strip for maintaining a layer of liquid on said tray, a sump disposed between the ends of the second trough, a flow component extending from the weir through the first trough to the sump forming a trap therewith through which to convey liquid overflowing from the weir to the second trough through said trap, and a hood supported above the edges of the first trough to form a second part of the vapor deflector for conducting rising vapor into the vapor duct beneath said bubble plate.

2. A distillation column comprising a plurality of bubble plate structures or contact trays disposed one above the other, each contact tray comprising a framework, and a plurality of self-contained units detachably secured to the framework and arranged side by side in spaced relationship to provide between them flow spaces for rising vapor, each unit comprising a length of perforated strip forming the bubble plate, a first longitudinal trough wider than the strip, means supporting the strip in the trough and spaced from its base to leave a vapor duct between them, the edges of the trough extending at each side beyond the strip to form one part of a vapor deflector, a second trough open at both ends to discharge liquid therefrom, means securing the second trough below the first trough to be'closed on the topside from end to end by said first trough to form a liquid transfer duct, an overflow weir disposed between the ends of the perforated strip for maintaining a layer of liquid on said tray, a sump disposed between the ends of the second trough, a flow component extending from the weir through the first trough to the sump forming a trap therewith through which to convey liquid overflowing from the weir to the second trough through said trap, and a hood supported above the edges of the first trough to form a second part of the vapor deflector for conducting rising vapor into the vapor duct beneath said bubble plate, each bubble plate structure or contact tray further comprising a feed trough carried by said frame work and disposed around said plurality of units to receive liquid from the open ends of the transfer ducts of the structure next above, the feed trough having an overflow weir to distribute the liquid to the perforated strips of the various units.

References Cited in the file of this patent UNITED STATES PATENTS 1,796,135 Alexander Mar. 10, 1931 1,876,800 Van Acker Sept. 13, 1932 2,651,512 Voleau Sept. 8, 1953 2,759,720 Kittel -e Aug. 21, 1956 FOREIGN PATENTS 693,413 Germany July 9, 1940 704,405 Great Britain Feb. 24, 1954 

